Toyota Prius Gen2 Inverter

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Prius Gen 2 Inverter Montage
Internal look at the Prius Gen2 Inverter
Prius Gen 2 Layout.jpg

The Toyota Prius is a hybrid vehicle. Their inverters are suitable and attractive for DIY EVs because of:

  • Large part availability, Priuses have been made in large numbers for 20 years and spares are inexpensive.
  • High affordability. Prius inverters are available for around $150 from scrapyards everywhere.
  • Durability. Toyota engineers appear to have made the inverters foolproof, many inputs and outputs gracefully handle fault conditions.
  • Respectable performance. Rated for 50kW output, but tested to handle 600v, and 350+A for MG2 inverter, 250+A for MG1 inverter, 360kW total (480hp)
  • Ease of re-purposing. Emulating the original ECU seems reasonably feasible.

The Gen2 Prius (2004-2009 model years) has a variety of useful components inside the inverter package:

  • 2 high power inverters, for the 2 motors MG1 (starter) capable of handling 250 amps, and MG2 (drive motor) capable of handling 350 amps.
  • A DC-DC converter to provide 12v and up to 100amps power supply to the automotive systems and accessories.
  • A tertiary power inverter to run the A/C, CAN controlled via the "BEAN" (????) network
  • A boost module to boost the 200v battery pack up to 500v, which looks to be able to function as a battery charger (wish list for future development)
  • See this video for a thorough disassembly and explanation of the Gen2 Inverter (Timestamp 1:15:30):
  • See this video for a more brief explanation of the above noted disassembled Gen2 HV System Operation:

Note that there is also a Toyota_Prius_Gen3_Board for the 2010-2015 model years.

Replacement Controllers

Re-purposing a Prius Gen2 Inverter outside of a Prius is done simply with add-on controllers that replace the vehicle's wiring harness and ECU.

32-pin Prius Inverter Pin mapping

Note: Wire colors on the male/female side of the 32-pin "i10" connector do not match. The inverter-side plug uses an almost unique color scheme, but the wiring harness side reuses many colors - unique only to a given shielded cable (of which there are 5), plus some extra unbundled wires. To save time chasing wires, you can find anything in the same bundle, and know the rest by noting which other colors are in that cable. There are also a few loose wires not bundled into a cable or shielded.

Note 2: The 12v supply rail for the "i9" connector also changes color at the wiring harness. The thicker blue loose wire is positive, the thick loose white-black wire is the ground.

Note 3: There is also an enclosure safety connector, this is the thin blue loose wire on the wiring harness.

32-pin Prius Inverter Pin Numbering
32-pin Prius Inverter Pin Numbering
32-pin Prius Inverter Pin Numbering
32-pin Prius Harness Pin Numbering
32-pin Prius Harness Pin Numbering
32-pin Prius Inverter Colors
32-pin Prius Inverter Harness Connections
32-pin Prius Inverter i9 12v DC
32-pin Prius Inverter Harness Cables

Pin # Designation Description Wire Color

(Inverter Side)

(See pictures to the right)

Wire Color

(Harness Side)

1 vacant
2 GIVA MG1 Phase Current V LightGreen White - Cable 1
3 GIVB MG1 Phase Current V Purple-Red Black - Cable 1
4 GUU MG1 PWM U - Speed Signal Wave Blue Black - Cable 2
5 GVU MG1 PWM V - Speed Signal Wave Blue-Red Green - Cable 2
6 GWU MG1 PWM W - Speed Signal Wave Yellow Yellow - Cable 2
7 MIVA MG2 Phase Current V LightGreen-Black Green - Cable 3
8 MIVB MG2 Phase Current V Purple-Yellow White - Cable 3
9 MUU MG2 PWM U - Speed Signal Wave Blue-Black Black - Cable 4
10 MVU MG2 PWM V - Speed Signal Wave Blue-Yellow White - Cable 4
11 MWU MG2 PWM W - Speed Signal Wave Yellow-Black Red - Cable 4
12 VH Inverter Capacitor Voltage Purple Yellow - Cable 3
13 CPWM Boost converter PWM switch signal Blue Black - Cable 5
14 CT Boost converter temperature sensor Green-Red Red - Cable 5
15 VL Boost converter input voltage Purple-White Yellow - Cable 5
16 GINV Inverter Ground Black-White Yellow - Cable 4
17 vacant
18 GIWA MG1 Phase Current W Grey Red - Cable 1
19 GIWB MG1 Phase Current W Grey-Black Green - Cable 1
20 GSDN MG1 Shutdown Brown-Black Red - Cable 2
21 GIVT MG1 Inverter Temperature Green-Black White - Cable 2
22 GFIV MG1 Inverter Fail White-Grey Grey
23 MIWA MG2 Phase Current W Grey-Green Red - Cable 3
24 MIWB MG2 Phase Current W Grey-Red Black - Cable 3
25 MSDN MG2 Shutdown Brown Green - Cable 4
26 MIVT MG2 Inverter Temperature Green Light Blue - Cable 4
27 MFIV MG2 Inverter Fail White Green
28 OVH Overvoltage Pink Brown
29 CSDN Boost converter shutdown signal Brown-White White - Cable 5
30 FCV Boost converter fail signal White-Red White
31 OVL Boost converter over voltage signal Pink-Blue Black
32 GCNV Boost converter ground Black-Red Green - Cable 5

(Article continues below)

Toyota gen2 dimension.png

DC-DC Converter

Prius gen 2 inverter lower casing internals
Prius Gen2 DC-DC connections.
DC-DC converter "C 5" connector

The onboard DC-DC Converter is powered by the high voltage traction battery to supply 12v and up to 100A for low-voltage automotive components and 12 battery maintenance, equivalent to an alternator or generator. Direct control of the converter is simple, only one 12v wire connected to Pin#1 of connector "C5" is necessary to activate it, but a second input can be added at Pin#4, to enhance control.

All 6-pin connectors are Yazaki 7283-7062-40, including the resolver connections on the transaxle.

The 6-pin "C5" connector terminal positions and harness-side colors:

Pin # Designation Description Wire Color
1 IGCT 12v+ Blue
2 ID1 Not Needed Purple
3 S B+ (opt) White
4 NODD 0-5v+ Ppl/Gld
5 VLO Not Needed Blue
6 Vacant

The case of the inverter must be vehicle ground (12v battery negative terminal), just as an alternator or generator would be.

With the HV bus energized and switched 12v applied to Pin#1 of "C5", the DC-DC will produce 13.2-15.2 Vdc on the large C6 single-conductor connector nearby, which is equivalent to a 12v alternator/generator positive terminal. Depending on voltage applied to pin 4 (if used), output can be tailored; when grounded, it will act as a "KILL" input and DC-DC output will drop to zero. No base load is required to produce voltage.

Note: The output at C6 (large grey connector) is not internally fused and not disabled unless power to Pin#1 of C5 is off, or Pin#4 is grounded, but the DC-DC converter can only produce output when the HV bus is energized.

Note on Limitations - The DC-DC system is not designed to charge up a low 12v battery and certainly not one that's completely dead, doing so can damage the inverter/converter. Pin#1 can be tied directly to the same ignition switch signal as the control board receives as this circuit draws only about 6.3mA.

Buck/Boost Converter

The inverter also has an onboard buck/boost converter that - when needed - can boost the ~200v battery pack up to 600v to send to the motors, and buck down high voltage generated by the motors in regen mode to recharge the batteries. See 'Charging' section below for how the buck/boost converter has been used for AC charging. See link below for another method of controlling the buck/boost converter.

Alternative Method: Control of Prius Gen2 Buck/Boost converter for low voltage CCS charging

Inverter Cooling

The inverter is liquid cooled, coolant enters at the front and exits the rear of the inverter housing from the o-ring port connected to the Hybrid Synergy Drive (HSD) cooling system reservoir. Some type of circulating pump and radiator are needed to use Toyota inverters, many compact options are available.


Details on connectors and terminals have been posted on the IH8MUD website:

Alternatively, the Toyota wire repair book can be found here:

Please use either or both of the above to identify the connector and terminal numbers needed for your project.

Connector Male Female
C5 90980-10988 90980-10987
B+ (DC-DC output) 90980-11963
32-pin connector TE 1318747-1 (& 1123343-1 for pins)
28-pin connector (on inverter logic board) TE 1565380-1 (& 1123343-1 for pins)


The gen 2 can only charge in buck mode. So maximum charge voltage is limited to the rectified AC input. E.G. From a 230 VAC source the inverter can only charge up to around 320VDC

Relevant Parameters

Charge mode:Buck

Chargecur: 1.5

Chargekp 20

Chargeki: 10

Chargeflt 2 dig

Charge pwmmin: 10 (Change this to get equivalent to min battery voltage.)

udcswbuck: x (HV bus voltage at which point Ground signal is used to control AC and HV battery relays)

Relevant Pins

  • CSDN (pin 29 on inverter)
    • Shuts down high and low IGBTs when fed 12v, via 470R
    • When CSDN is HIGH both IGBTs are OFF.
  • CPWM(pin 31 on control board, 13 on inverter)
    • Enables charge mode when fed 12v via 470R
    • When CPWM is HIGH, the LOW side IGBT is on(shorts out battery), when CPWM is LOW the HIGH side IGBT is on.
  • Forward and reverse (11 and 12 on control board)
    • Both must be high to enable charging
  • DCSW switch(15 in control board)
    • Controls DC relay switch.

Physical setup

  • 240v AC plugs into two MG1 phases, with a precharge resistor always on.
    • Relay controlled by DCSW pin connected to ground side of relay signal wires.
  • HV Battery connected with precharge resistor
    • Relay controlled from DCSW pin connect to ground side of relay wires.
  • CPWM to 12v via 470R resistor. Pulled high to when you want to charge
  • CSDN pin to 12v via 470R resistor. Pulled high to when you want to charge
    • CSDN pin also tied to DCSW signal pin, which pulls it down when precharge is complete.


  1. Fwd and reverse signals high, relays open
  2. CPWM and CSDN pulled high via 470R .
  3. Connect AC input voltage with precharge
    1. DCSW will then close relays and pull down CSDN pin to activate charging.
  4. Activate buck on charger. (By manual web interface or does just having FWD and Reverse high activate this?
  5. To stop, can change chargecur to 0 or switch off inverter power.

Offgrid AC Use

There has been moderate success using the Prius Gen 2 inverter to generate AC outlet voltages for offgrid use.



External Links - Physical destructive teardown of the Gen2 inverter.